What about booking an AirBNB someplace fun? You could book the place to stay, nail down flights, rent a car, and just explore someplace.
I've poked around before at places in Key West, Boston, Texas, and other locations that have all kinds of cool stuff to do that doesn't require a crazy schedule.
There's also the Disney/Universal option where you can set it all up through a planner. If you want to do that let me know I have contacts. Wife and I did that for our honeymoon and a vacation and it was fun.